Suppose we have two strings s and t of same length. Consider an operation where we choose two indices in a string (not necessarily different) and swap the characters at the selected indices. We have to check whether it is possible to make both strings same by performing at most one string swap on exactly one of the strings or not.
So, if the input is like s = "hello" t = "hlelo", then the output will be True because we need to swap 'e' and 'l' at either s or t to make them equal.
To solve this, we will follow these steps −
st := a new set
st2 := a new set
for i in range 0 to size of s, do
if s[i] is not same as t[i], then
diffs := diffs + 1
if s[i] not present in st, then
insert s[i] into st
if t[i] not present in st2, then
insert t[i] into st2
if diffs > max_diffs, then
return true if (diffs is same as 0 or diffs is same as 2) and size of st is same as size of st2 and st is same as st2, otherwise false
Let us see the following implementation to get better understanding −
def solve(s, t): max_diffs=2 diffs=0 st = set() st2 = set() for i in range(len(s)): if s[i] != t[i]: diffs+=1 if s[i] not in st: st.add(s[i]) if t[i] not in st2: st2.add(t[i]) if diffs > max_diffs: return False return (diffs == 0 or diffs == 2) and len(st) == len(st2) and st == st2 s = "hello" t = "hlelo" print(solve(s, t))